This invention relates to a transport unit for transporting print medium, and in particular to a transport unit placed in a paper discharge section of a printer for handling long print paper.
A printer contained in an apparatus installed in an environment with no humans in attendance or an environment in which the operator cannot frequently replace paper, such as an ATM (automated-teller machine) or a POS (point-of-sale) cash resister is known. Printers of this type typically print on continuous paper, such as rolled paper, and then cut the paper with a cutter mechanism, after which the cut paper is discharged. These printers are widely used for the purpose of reducing, as much as possible, the frequency of paper replacement.
In this kind of printer, discharge control of paper is important. In a normal printer, the leading end of paperxe2x80x94after print termination or during a printing operationxe2x80x94is discharged through an outlet to the outside of the cabinet by the paper feed operation accompanying the printing operation. However, if the user attempts to pull on the paper being discharged from the outlet before the paper is cut by the cutter mechanism, it causes a print failure or a paper jam to occur.
To prevent such a problem, in a related art paper discharge unit used with a printer, for example, as disclosed in Japanese Patent Publication No. 9-142708A, paper feeding, with a discharge roller placed in the proximity of an outlet, is temporarily stopped during the printing operation, the paper is curved like a loop in the paper discharge unit to preventing a leading end of the paper from extending through the outlet, and after the printing operation is terminated, the paper feeding is restarted to discharge the paper. To curve the paper, the paper discharge unit comprises a paper guide, which normally guides the paper straight toward the discharge roller, but which, when the paper feed stops, is displaced such that the paper is curved like a loop at a predetermined space upstream of the discharge roller.
The above paper guide is formed of an elastic plate made up of a synthetic resin plate, a thin metal plate, etc., with an end part on the discharge roller side fixedly secured. The leading end part of printed paper is guided toward the discharge roller, and the transport force of the paper bends the paper guide, so that the paper is curved like a loop and is retained in the predetermined space.
As another example, a paper guide can be rotated with an end part on the discharge roller side as a supporting shaft. In this case, the paper guide may be moved as transported paper is curved (Japanese Patent Publication No. 11-79468A, for example) or may be moved by an actuator such as a solenoid (Japanese Patent Publication No. 1-181659A, for example).
However, in the related art configuration, wherein one end of the paper guide is fixedly secured and paper is curved like a loop by the elastic force of the paper guide, the strength of the paper guide must be increased for suppressing the bending amount to improve the paper guide""s ability to guide paper into the discharge roller. On the other hand, the strength of the paper guide must be lowered to provide a sufficient bending amount to stably curve the paper. That is, the function of reliably guiding the leading end part of printed paper toward the discharge roller, and the function of curving the paper so that the curved paper is retained in the predetermined space, are mutually exclusive.
In the related art configuration, wherein the paper guide can be configured to curve paper by rotating it with one end thereof as the supporting shaft, if a xe2x80x9cpeculiarityxe2x80x9d exists at the leading end of paper sent from the print section, the paper guide is irregularly rotated because of the transport force and the peculiarity. Thus, the paper is not well guided into the discharge roller and enters the outside of the transport path, causing a paper jam to occur.
It is, therefore, an object of the invention to provide a transport unit that can reliably guide paper into an outlet even if the leading end of the paper has a xe2x80x9cpeculiarityxe2x80x9d or the like, thereby circumventing transport trouble of a paper jam, or the like.
In order to achieve the above object, according to the present invention, there is provided a transport unit, for transporting a print medium, comprising:
a guide member, that forms at least a part of a transport path through which the print medium is transported;
a support member, that supports the guide member so as to be movable between a first position at which the guide member forms the transport path and a second position at which the guide member opens the transport path; and
a lock member, which locks the support member at the first position.
In this configuration, since a movement of the guide member is locked when the leading end of the print medium is guided into the guide member, even if a xe2x80x9cpeculiarityxe2x80x9d or the like occurs at the leading end of the print medium, the print medium is guided through the transport path smoothly and reliably. When the print medium is bent due to the transporting force, the guide member is unlocked so that the print medium can be curved like a loop and stored in a predetermined space. That is, the guide member is switched between the locked state in which the print medium can be reliably guided into the transport path, and the unlocked state in which the print medium can be curved like a loop.
Preferably, the transport unit further comprises a moving mechanism that moves at least one of the guide member and the lock member between a third position and a fourth position. The guide member includes a first engagement member, and the lock member includes a second engagement member. The first engagement member and the second engagement member are engaged with each other at the third position, and are separated from each other at the fourth position.
Here, it is preferable that the first engagement member is provided as a pair of engagement members arranged on the guide member at both widthwise sides of the print medium. The second engagement member is provided as a pair of engagement members arranged on the lock member at both widthwise sides of the print medium.
Also, it is preferable that the transport unit further comprises:
an outlet, from which the print medium is discharged;
a first transport roller, which transports the print medium toward the outlet, in the transport path at a downstream side of the guide member;
a controller, which controls the moving mechanism to move the at least one of the guide member and the lock member toward the third position to lock the guide member, when a leading end of the print medium reaches the guide member, and controls the moving mechanism to move the at least one of the guide member and the lock member toward the fourth position to unlock the guide member, when the leading end of the print medium reaches in the vicinity of the first transport roller.
In this configuration, switching of the guide member between the locked state and the unlocked state can be controlled electrically.
In this case, it is preferable that the transport unit further comprises a second transport roller, which transports the print medium toward the guide member, in the transport path at an upstream side of the guide member. The controller determines a timing to move the at least one of the guide member and the lock member based on a rotation amount of the second transport roller.
Also, it is preferable that the lock member is rotatably supported at an upstream side of the first transport roller. The lock member includes a path switcher that is placed in the transport path to lead a rear end of the print medium toward another transport path, when the first transport roller transports the print medium backward.
In this configuration, if the print medium discharged through the outlet is not removed, the print medium can be fed backward and can be collected.
Preferably, the support member rotatably supports the guide member such that a portion of the guide member placed in an upstream side of the transport path opens the transport path.
Here, it is preferable that the lock member is arranged to face the guide member so as to form, together with the guide member, the transport path. The guide member is formed with a first slot that extends in a direction substantially perpendicular to the transport path. The support member includes a shaft member that is engaged with the first slot to rotatably support the guide member. And the moving mechanism includes the first slot and the shaft member.
In this configuration, the guide member can be switched between the locked state and the unlocked state using the thickness of the transported print medium, and can be switched according to a simple structure without using a power source.
The first slot may be replaced with a groove and the shaft member may be replaced with a projection.
Here, it is preferable that the moving mechanism further includes a first urging member that urges the guide member toward the lock member.
In this configuration, if the print medium does not exist in the proximity of the engagement part, the guide member reliably can be locked.
Also, it is preferable that a gap is formed between the guide member and the lock member at the third position such that the narrowest part of the gap is narrower than a thickness dimension of the print medium. An engagement margin is provided, between the first engagement member and the second engagement member at the third position, so as to be smaller than the thickness dimension of the print medium.
Still also, it is preferable that the guide member includes an engagement releaser that is protruded toward the transport path. The first engagement member is formed on the guide member so as not to be protruded from an outer peripheral face of the engagement releaser. Also, the lock member is formed with a recess which houses the engagement releaser and the first engagement member, being formed with side walls. The second engagement member is provided as one of the side walls forming the recess.
Alternatively, the lock member is formed with a first housing member which houses the engagement releaser, and a second housing member which houses the first engagement member. The second engagement member is provided as one of side walls formed with the second housing member.
In this configuration, the locked guide member can be unlocked independently of the thickness of the print medium.
Preferably, the transport unit further comprises a reliever that moves the guide member through use of a force acting between the first engagement member and the second engagement member to rotate the guide member when the first and second engagement members are placed in the third position. The reliever moves the guide member by displacing the shaft member toward a downstream side of the transport path.
In this configuration, if the guide member needs to be rotated for opening the transport path for maintenance of a paper jam, for example, the guide member can also be unlocked while the force acting on the engagement part of the guide member and the lock member is relieved, so that damage to the engagement part is prevented.
Also, it is preferable that the reliever is formed with a bearing member that supports the shaft member movably therein.
Further, it is preferable that the bearing member is provided as a second slot which extends in substantially parallel with the transport path.
Moreover, it is preferable that the reliever includes a second urging member that urges the first engagement member toward the third position.
Preferably, the print medium is provided as continuous paper. Alternatively, long cut sheets may be provided as the print medium.
According to a preferred embodiment, the guide member rotates as print medium is transported, so that a part of the medium is always in contact with the guide member and if the guide member is provided with a member for regulating the widthwise position of the medium, a skew of the print medium is during the transporting can be prevented, so that stable transporting can be accomplished.
According to the present invention, there is also provided a printer comprising the above transport unit.
Also, according to the present invention, there is provided a control method used in the above transport unit, comprising the steps of:
rotating the second transport roller to transport the print medium;
driving the lock member to lock the guide member; and
driving the lock member to unlock the guide member, when the leading end of the print medium reaches in the vicinity of the first transport roller.
According to the present invention, there is also provided a computer program executed by the controller in the above transport unit, comprising the above-noted steps.